1. Field of the Invention
The present invention generally relates to an active device capable of converting an electrical signal into a voltage, more specifically, to a magnetic recording head consisting of either an anisotropic-magneto-resistive (hereinafter referred as AMR) or giant magneto-resistive (hereafter referred as GMR) sensor along with an insulation spacer and magnetic shields.
2. Description of the Related Art
As is well known in the field, the insulating spacer in an anisotropic magneto-resistive/a giant magneto-resistive device (hereinafter referred to as AMR/GMR) used for magnetic recording is becoming thinner and thinner in order to increase a linear recording density. Inevitably, we are facing electric-pop noise resulting from the thinner spacer. For high manufacturing yield and reliability of electric and magnetic performance, such electric-pop noise must be eliminated.
U.S. Pat. No. 3,864,751 entitled xe2x80x9cInduced Bias Magneto-resistive Read Transducerxe2x80x9d issued to Beaulier and Napela, on Feb. 4, 1975 proposed that a SAL is isolated from a magneto-resistive device (referred to as MR hereinafter). The patent did not reveal any methods how to make it. Another key point is that the MR and SAL are electrically isolated. In the prior art described by Beaulieu et al., electric-pop noise is present if a thinner insulating spacer ( less than 150 xc3x85), such as Al2O3, is used. Otherwise, the devices would need a thicker SAL to bias the MR if a thicker insulator spacer (2-400 xc3x85) were used. There are two problems associated with the latter case. Firstly, the SAL can not be easily saturated by a current in the MR and an antiferromagnetic pinning layer must be used to pin the SAL so that the SAL magnetization is perpendicular to the current direction. In this case, the device process becomes very complicated and it also renders designs less extendible to a narrower shield to shield spacing for higher density recording.
The SAL has a function as a shunt bias layer in SAL biased AMR devices. When the MR and SAL are spaced by electric conducting materials, such as Ta, the SAL and MR devices have the same electric track width. These configurations have been disclosed in U.S. Pat. No. 4,663,685 issued in 1987, to C. Tsang, U.S. Pat. No. 4,639,806 issued in 1987 to T. Kira, T. Miyagachi, and U.S. Pat. No. 5,018,037 issued to M. T. Krounbi, O. Voegeli and P. Wang.
Accordingly, one objective of this invention is to provide an AMR design with a thin insulating spacer free of electric-pop noise.
Another objective is to provide a SAL biased AMR product using an insulated spacer.
A further objective of this invention is to provide an electric active device free of electric-pop noise over an insulating spacer on the top of an electric conductor.
Still another objective of this invention is to provide a design to eliminate electric-pop noise between an AMR/GMR active device and shields.
In accordance with one aspect of the present invention, a magnetoresistive device comprising:
a magnetosresistive layer;
a soft-adjacent magnetic transverse bias layer (SAL);
an insulating layer arranged between said magnetosresistive layer and said magnetic transverse bias layer;
a conductive layer contacting electrically both said magnetosresistive layer and said magnetic bias layer at at least one end region of said SAL element.
In accordance with another aspect of the present invention, a magnetoresistive device comprising:
a first shield;
a second shield;
an AMR/GMR device;
a first insulating gap layer between said AMR/GMR and one of said shields;
a second insulating gap layer between said AMR/GMR and another of said two shields;
a conductive layer contacting electrically said AMR/GMR device to either one of said shields.
In accordance with a further aspect of the present invention, a hard disk driver is provided with the magnetoresistive device.
Compared to the prior art by Tsang, Kire et al and Kroumbi et al, this invention provides an AMR sensor with much improved signal. The signal improvement can be as much as 90% provided that the same MR/SAL device and operating current are used for the device.